'Not bad,' says Microsoft manager; but what does the number mean?

Microsoft on Monday said that customers had downloaded about 27 million copies of the Office for iPad apps in six weeks, a number one analyst called "promising" even as she noted that it lacked important contextual details.

"I think it's too early to know how much traction they're actually getting," said Melissa Webster, an analyst with IDC, in an interview. "The more interesting question is how much revenue [Microsoft] has generated from people who were motivated to sign up for Office 365."

Julia White, a general manager in the Office group, cited the 27-million download figure during the keynote at TechEd 2014, a Microsoft conference that kicked off Monday in Houston.

"Looks like we have about 27 million downloads of these apps. Not bad," said White. As she demonstrated how IT departments can manage iPads with Intune, the screen showed that more than 12 million of those downloads were tagged to U.S. users.

Because there are four discrete apps in the Office for iPad line -- Word, Excel, PowerPoint and OneNote -- White's comment implied that the 27 million tally was of all apps, not the number of "sets" or the total number of customers who have one or more of the quartet on their iPads.

According to AppAnnie, Word was downloaded the most -- it typically was the highest of the four on the mobile app analytics vendor's most-downloaded list -- with Excel, PowerPoint and OneNote following, in that order.

Because of Microsoft's in-isolation download count, anything else, such as the number of Office for iPad users, was pure guesswork. If each customer downloaded an average of two of the four apps, for instance, Microsoft's figure would represent 13.5 million users. But bump up the average to three, and the user base slips to 9 million.

Apple has sold a total of 211.6 million iPads since the tablet's 2010 introduction. But because Office for iPad requires iOS 7 -- and that OS won't run on the original iPad -- a better number would be 182.8 million, which represents all devices sold from April 2011, the first full month after the debut of the iPad 2, through March 2014.

Using arbitrary apps-per-user averages of 3 and 2 would mean Office for iPad is on between 5% and 7% of all iPads. As an outlier, if each user downloaded just one of the apps, the percentage would jump to almost 15%.

Benedict Evans, an analyst with the venture capitalist firm Andreesen Horowitz, pegged Office's penetration in similar terms. "27m Office for iPad downloads: depending on how many people downloaded multiple apps, say 5-15% of the iPad base," Evans tweeted Monday.

But as Webster pointed out, the big question -- how much revenue those downloads have produced -- is murkier.

The 27 million can't be used to deduce the number of paying customers because the Office for iPad apps can be downloaded free of charge for viewing documents, spreadsheets and presentations. (Unlike Word, Excel or PowerPoint, the free OneNote app offers full functionality.) To activate advanced features -- including document creation and editing -- users must have a valid subscription to an Office 365 rent-not-buy plan.

Microsoft has given little insight into the success of Office 365, and none into what part Office for iPad may have played. Microsoft's most regularly-touted number has been the active subscriptions to Office 365 Home, the pricier of two consumer-grade plans.

Word for iPad has been downloaded the most of any of the suite's iOS apps, according to lists kept by trackers like AppAnnie.